XAUSA nailed it perfectly ... I bought my first Springfield 1903 back in 1958 and, based on the American Rifleman ad by Numrich for this " one piece safety firing pin, with crisp speed lock action", I spent the $3.75 for one of them ( along with $3.50 for two new 1911 pistol magazines with pouch). I still have the rifle, but I reinstalled the original firing pin assembly and gave this 'rare & desirable one piece firing pin" to a buddy who needed a new striker years ago. Numrich advertised that lock time was reduced by nearly 50% with it, but I never noticed the difference!